5FF1

Two way mode of binding of antithyroid drug methimazole to mammalian heme peroxidases: Structure of the complex of lactoperoxidase with methimazole at 1.97 Angstrom resolution


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.97 Å
  • R-Value Free: 0.226 
  • R-Value Work: 0.177 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Dual binding mode of antithyroid drug methimazole to mammalian heme peroxidases - structural determination of the lactoperoxidase-methimazole complex at 1.97 angstrom resolution.

Singh, R.P.Singh, A.Sirohi, H.V.Singh, A.K.Kaur, P.Sharma, S.Singh, T.P.

(2016) Febs Open Bio 6: 640-650

  • DOI: 10.1002/2211-5463.12051

  • PubMed Abstract: 
  • Lactoperoxidase (LPO, EC 1.11.1.7) is a member of the mammalian heme peroxidase family which also includes thyroid peroxidase (TPO). These two enzymes have a sequence homology of 76%. The structure of LPO is known but not that of TPO. In order to det ...

    Lactoperoxidase (LPO, EC 1.11.1.7) is a member of the mammalian heme peroxidase family which also includes thyroid peroxidase (TPO). These two enzymes have a sequence homology of 76%. The structure of LPO is known but not that of TPO. In order to determine the mode of binding of antithyroid drugs to thyroid peroxidase, we have determined the crystal structure of LPO complexed with an antithyroid drug, methimazole (MMZ) at 1.97 Å resolution. LPO was isolated from caprine colostrum, purified to homogeneity and crystallized with 20% poly(ethylene glycol)-3350. Crystals of LPO were soaked in a reservoir solution containing MMZ. The structure determination showed the presence of two crystallographically independent molecules in the asymmetric unit. Both molecules contained one molecule of MMZ, but with different orientations. MMZ was held tightly between the heme moiety on one side and the hydrophobic parts of the side chains of Arg255, Glu258, and Leu262 on the opposite side. The back of the cleft contained the side chains of Gln105 and His109 which also interacted with MMZ. In both orientations, MMZ had identical buried areas and formed a similar number of interactions. It appears that the molecules of MMZ can enter the substrate-binding channel of LPO in two opposite orientations. But once they reach the distal heme pocket, their orientations are frozen due to equally tight packing of MMZ in both orientations. This is a novel example of an inhibitor binding to an enzyme with two orientations at the same site with nearly equal occupancies.


    Organizational Affiliation

    Department of Biophysics All India Institute of Medical Sciences New Delhi India.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Lactoperoxidase
A, B
595Capra hircusMutation(s): 0 
Gene Names: LPO
Find proteins for A3F9D6 (Capra hircus)
Go to Gene View: LPO
Go to UniProtKB:  A3F9D6
Small Molecules
Ligands 6 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MMZ
Query on MMZ

Download SDF File 
Download CCD File 
A, B
1-METHYL-1,3-DIHYDRO-2H-IMIDAZOLE-2-THIONE
METHIMAZOLE
C4 H6 N2 S
PMRYVIKBURPHAH-UHFFFAOYSA-N
 Ligand Interaction
GOL
Query on GOL

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Download CCD File 
A, B
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
CA
Query on CA

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Download CCD File 
A, B
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
HEM
Query on HEM

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Download CCD File 
A, B
PROTOPORPHYRIN IX CONTAINING FE
HEME
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
NO3
Query on NO3

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Download CCD File 
A, B
NITRATE ION
N O3
NHNBFGGVMKEFGY-UHFFFAOYSA-N
 Ligand Interaction
NAG
Query on NAG

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Download CCD File 
A, B
N-ACETYL-D-GLUCOSAMINE
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.97 Å
  • R-Value Free: 0.226 
  • R-Value Work: 0.177 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 80.310α = 90.00
b = 93.020β = 89.97
c = 81.530γ = 90.00
Software Package:
Software NamePurpose
REFMACrefinement
SCALEPACKdata scaling
HKL-2000data reduction
AMoREphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2016-01-13
    Type: Initial release
  • Version 1.1: 2016-07-27
    Type: Database references